(I developed this strategy because I kept getting discovered by other players.)
- Find a Storage Crate.
- Find a Rowboat (or not, there's usually one where you're heading).
- Head to Devil's Ridge.
- Scuttle your Ship or let it sail away (so as to not alert other players of your presence on the island).
- Jump down to this location, visible from the harbor.
From this spot you'll fish undisturbed by skeletons, with a good view of potential visitors. You can't be seen from behind or above.
You can hide your Storage Crate and yourself right behind you. This and the view makes Devil's Ridge safer than Mermaid's Hideaway for Pondie-fishing in my opinion.
Above and below are Cooking Spots, but in my opinion cooking is not worth the risk as you can catch two Pondies in the time it takes to cook one while cooking doesn't double your profit.
Warning: Don't die or take the Mermaid if you're solo or alone on the island, as this can trigger a server merge and despawn your Storage Crate.
- When you're done fishing, wait for sunset, take your Storage Crate to your Rowboat, and start rowing east.
If you don't get to Roaring Traders Seapost before sunrise, you're not a true Pondie Ninja.
(By the way, fishing is not an efficient way to level up Hunter's Call. If that's your goal, sell them Mermaid Gems instead.)
